6 m
Top opening
Where we usually go in, so that the swim through the rock is downwards.
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Sail Rock
diving guide
A granite pinnacle alone in the open sea between Koh Phangan and Koh Tao, rising from 40 metres to above the surface. Schools of barracuda and batfish, a swim-through called The Chimney and, some days, a whale shark. This is what to expect, when to go and how to dive it.
Sail Rock · open sea, one hour out
The site · Hin Bai
One rock,
open sea
Sail Rock — Hin Bai in Thai — stands alone in open water, far from any reef. With nowhere else to shelter, the fish of the open sea gather around it: that is why it is the best dive site in the Gulf and the one almost every diver on Koh Phangan and Koh Tao wants to see.
The rock drops away on all sides, so there is a depth for every level: new divers stay on the upper walls, certified divers circle the pinnacle deeper, and Deep divers can reach the sandy bottom at 40 metres.
- Depth
- 5–40 m
- From Chaloklum
- 1 hour
- Level
- All
- Water
- 28–30°C
- Current
- Variable
The walls of Sail Rock
The Chimney
A tunnel
through the rock
Sail Rock's signature feature is a vertical tunnel through the middle of the pinnacle. The top opening is at 6 metres, the bottom one at 18 metres, and halfway down a window in the wall opens out between 10 and 14 metres.
It can be swum from the top down, from the bottom up, or entered and left through the window. We prefer top to bottom: going down avoids any uncontrolled ascent. No special course is needed — unlike a cave, it is open to the surface above, so in an emergency you can always go straight up. Your guide decides on the day, depending on your level.
10–14 m
The window
A crack in the wall halfway down, and another way in or out.
18 m
Bottom opening
The way out at the bottom, back onto the wall of Sail Rock.
What you will see
Big schools,
big visitors
Sail Rock is about fish in numbers. Schools hang in the blue off the walls, and the larger visitors come in from the open sea to feed on them.
All year
Barracuda (Sphyraena spp.)
Great spiralling schools, often right beside the rock. The picture most divers take home from Sail Rock.
All year
Batfish and trevally (Platax spp., Caranx spp.)
Curious batfish that come close to look at you, and trevally hunting along the edges of the schools.
With luck
Whale sharks (Rhincodon typus)
The biggest fish in the sea visits Sail Rock to feed on plankton. The textbook season is April to June, but we have seen them in February and September too.
When to go
Sail Rock
through the year
Sail Rock can be dived all year, and the water stays at 28–30°C. What changes is the visibility and what comes to visit.
Green water, big life
More plankton and visibility of about 5–10 m. That plankton feeds the big schools and brings in the whale sharks.
Whale shark season
The textbook months for whale sharks, with the water starting to clear. Never guaranteed, always hoped for.
Clearest water
Sail Rock at its clearest, often 20–30 m of visibility. The best months to see the whole pinnacle at once.
Monsoon
We stay open, but on days when the sea is unsafe the boat does not go out, and you get a full refund.
How to see it
A way in
for every level
We leave Chaloklum at 9:30 on our own boat, the Rungworawan, and usually arrive as the early boats are leaving. Two dives, a hot lunch on deck, and back at the pier around 15:30.
Certified divers
Fun Dive
Two guided dives with a maximum of four divers per guide. Deep Specialty divers can go down to the bottom at 40 m.
1 day3,200฿
DetailsLearn to dive
Open Water course
Your open-water training dives take place here, so you certify at the best site in the Gulf.
3 days12,900฿
DetailsNo diving needed
Snorkelling
The top of the rock is close to the surface, so snorkellers see the schools too — and sometimes a whale shark.
1 day1,500฿
DetailsQuestions
Sail Rock FAQ
Where is Sail Rock?
In the open sea between Koh Phangan and Koh Tao, in the Gulf of Thailand. From our pier in Chaloklum, on the north coast of Koh Phangan, it is about an hour by boat.
How deep is Sail Rock?
The rock rises from about 40 metres to above the surface. Most dives are between 5 and 30 metres; the bottom at 40 metres is for divers with the Deep Specialty.
Can beginners dive Sail Rock?
Yes. The shallow parts of the rock suit Try Dives and Open Water students, and our Open Water training dives run here. On days when the sea is rough, we may choose the calmer Koh Ma for beginners instead.
When is the best time to dive Sail Rock?
It can be dived all year. The water is clearest from about May to October, often with 20–30 m of visibility. From January to April there is more plankton and less visibility, but more life, and whale sharks are most likely from April to June.
Will I see a whale shark at Sail Rock?
Nobody can promise one. The textbook season is April to June, and we have also had great encounters in February and September. When one comes through, it is the dive of a lifetime.
What is The Chimney?
A vertical tunnel through the pinnacle, from 6 metres at the top to 18 metres at the bottom, with a window in the wall between 10 and 14 metres. We usually swim it from the top down to avoid uncontrolled ascents. It is open to the surface, so no special course is needed; your guide decides on the day whether it suits your level.
Is there current at Sail Rock?
Sometimes. Because it stands in open sea, the current changes from day to day, but it usually hits only one side of the rock. We plan every dive to avoid it and brief you on the boat before you get in.
Is it better to dive Sail Rock from Koh Phangan or Koh Tao?
Both islands run trips there. From Chaloklum it is about an hour by boat, and with our 9:30 departure we usually arrive as the early boats are leaving, so the rock is quieter.
How much does it cost to dive Sail Rock?
A Fun Dive day with two dives is 3,200฿ for certified divers, and a snorkelling trip is 1,500฿. Both include equipment, a hot lunch, fruit and drinks; underwater camera rental is 600฿.
Ready for
Sail Rock?
Tell us your level and your dates on WhatsApp, and we will tell you honestly what the sea is doing and which day to go.
See also our other dive sites around Koh Phangan.